Research Article


2019, 12(5): 1041–1047


Nitrogen-doped graphene quantum dots: Optical properties modification and photovoltaic applications

Md Tanvir Hasan1,§, Roberto Gonzalez-Rodriguez1,§, Conor Ryan1, Kristof Pota2, Kayla Green2, Jeffery L. Coffer2, and Anton V. Naumov1 (*)

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1 Department of Physics and Astronomy, Texas Christian University, TCU Box 298840, Fort Worth, Texas 76129, USA
2 Department of Chemistry and Biochemistry, Texas Christian University, TCU Box 298860, Fort Worth, Texas 76129, USA
§ Md Tanvir Hasan and Roberto Gonzalez-Rodriguez contributed equally to this work.

Keywords: nitrogen-doped graphene quantum dots, ozone treatment, optical properties, photovoltaics, solar cells
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  • Abstract
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In this work, we utilize a bottom-up approach to synthesize nitrogen self-doped graphene quantum dots (NGQDs) from a single glucosamine precursor via an eco-friendly microwave-assisted hydrothermal method. Structural and optical properties of as-produced NGQDs are further modified using controlled ozone treatment. Ozone-treated NGQDs (Oz-NGQDs) are reduced in size to 5.5 nm with clear changes in the lattice structure and ID/IG Raman ratios due to the introduction/alteration of oxygen-containing functional groups detected by Fourier-transform infrared (FTIR) spectrometer and further verified by energy dispersive X-ray spectroscopy (EDX) showing increased atomic/weight percentage of oxygen atoms. Along with structural modifications, GQDs experience decrease in ultraviolet–visible (UV–vis) absorption coupled with progressive enhancement of visible (up to 16 min treatment) and near-infrared (NIR) (up to 45 min treatment) fluorescence. This allows fine-tuning optical properties of NGQDs for solar cell applications yielding controlled emission increase, while controlled emission quenching was achieved by either blue laser or thermal treatment. Optimized Oz-NGQDs were further used to form a photoactive layer of solar cells with a maximum efficiency of 2.64% providing a 6-fold enhancement over untreated NGQD devices and a 3-fold increase in fill factor/current density. This study suggests simple routes to alter and optimize optical properties of scalably produced NGQDs to boost the photovoltaic performance of solar cells.
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Nitrogen-doped graphene quantum dots: Optical properties modification and photovoltaic applications. Nano Res. 2019, 12(5): 1041–1047

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